R&B star Chris Brown pleaded not guilty on Monday to charges that he threatened and assaulted his girlfriend, singer Rihanna. Brown arrived 25 minutes late for the 3pm arraignment, amid a flurry of last-minute plea bargain rumours. Rihanna was not present.

After judge Patricia Schnegg read the charges, of assaulting Rihanna "by means of force likely to produce great bodily injury" and of threatening to commit a crime "which would result in death and great bodily injury", the 19-year-old murmured his plea. "Not guilty, your honour," he said. They were the only words Brown spoke in court.

The singer spent less than 15 minutes at the Los Angeles superior court, entering his plea and then departing in a black SUV, escorted by four bodyguards.

The charges stem from an alleged altercation between the couple on the early hours of 8 February. According to a police affidavit, Brown shoved Rihanna's head against the passenger window, punched her in the face, bit her ear and finger and put her into a headlock. "I'm going to kill you," he allegedly told her.

Brown later said that he was "sorry and saddened" about the incident. He faces up to four years in prison if convicted.

Although Brown's attorney did not make a statement to the press, a lawyer for Rihanna spoke to reporters after the hearing. Donald Etra confirmed that Rihanna is in her native Barbados but would testify if subpoenaed. Asked directly if his client thought Brown is guilty, Etra said, "Her position on the case is to leave the matters of guilt or innocence to the judge and or defence counsel".

The two pop stars are thought to have reconciled, although they have not recently been seen together.